Math Is Fun Forum

the_white_sheep

Member

Registered: 2005-09-05

Posts: 9

Simultaneous equation: Easiest work out possible

Hi

I know this may look easy for some people but I'm just grasping it. Please look at the following simultaneous equation and see what you get. Thanks alot.

Please show me the easiest way to work this out so that I can apply it to other questions.

3p + 2q = 9
4p - 6q  = 25

Please let me know how you worked it out as well.

Thanks

Hozan

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Simultaneous equation: Easiest work out possible

We need to make one of the terms in one the equations equivalent to one of the terms in the other equation.

The easiest way to do this would be to multiply everything in the first equation by 3:

9p + 6q = 27
4p - 6q = 25

Adding these equations together cancels the 'q' terms, so we are left with 13p = 52 which gives p = 4.

Substitute p = 4 into one of the equations: (3x4) + 2q = 9 

12 + 2q = 9
2q = -3
q = -1.5

Check with the other: (4x4) - (6x-1.5) = 25
As that equation is meant to equal 25, that means that I got it right.

---

Why did the vector cross the road?
It wanted to be normal.

the_white_sheep

Member

Registered: 2005-09-05

Posts: 9

Re: Simultaneous equation: Easiest work out possible

thanks alot, great job